Battery Pack Switching Architecture for Safe Hot-Swapping
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Solution Overview
Problem
Conventional battery systems face challenges in efficiently hot-swapping battery packs with different charging states, temperatures, and use histories, leading to issues with voltage balancing, overcurrent, and uneven power distribution when connected in series or parallel, and fail to manage dynamic load demands effectively.
Innovation Solution
A dynamic battery management system with unidirectional switching elements and a controller that adjusts the connection architecture and switching modes to prioritize safety and operability, allowing independent control of charging and discharging paths, and dynamically calculates the maximum allowable current based on pack conditions and external load parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If battery packs with different voltage are connected in parallel, then the system can operate with maintained voltage level, but current flows from high voltage pack to low voltage pack causing overcurrent and overheating risks
Solution Approach 1:
The patent introduces a current balancing circuit as an intermediary component between battery packs of different voltages. This circuit actively manages current distribution, preventing direct uncontrolled current flow from high voltage to low voltage packs, thereby eliminating overcurrent and overheating risks while maintaining the ability to operate with voltage level maintenance.
Solution Approach 2:
The patent dynamically adjusts electrical parameters (current distribution, voltage balancing) through active control mechanisms. By changing these parameters in real-time based on the state of each battery pack, the system can safely connect packs with different voltages without causing harmful current flow, thus resolving the contradiction between power maintenance and harm prevention.
2Stability of the object's composition
If active balancing is used to mitigate voltage difference between battery packs, then voltage balance is improved, but conversion losses occur and time is required for the process
Solution Approach 1:
The current balancing circuit serves as an intermediary that enables direct current redistribution between battery packs without requiring conversion to other energy forms. This direct balancing approach reduces conversion losses compared to traditional active balancing methods while still achieving voltage balance between packs.
3Power
If battery packs are connected in series, then total voltage is increased, but a wide operating voltage range of load or voltage transformation means are required increasing complexity
Solution Approach 1:
The patent creates a parallel connection system with current balancing capability that can universally accommodate battery packs of different voltages. This multi-functional approach eliminates the need for voltage transformation means, as the system can directly connect packs in parallel while actively managing current distribution, thus reducing complexity while maintaining power output.
4Power
If multiple battery packs are coupled in parallel, then voltage level is maintained, but packs must be of very close voltage initially requiring significant time for voltage equalization
Solution Approach 1:
The current balancing circuit performs preliminary voltage equalization through controlled current distribution before full parallel operation begins. By pre-balancing the voltage levels of connected packs through active current management, the system reduces the time required for voltage equalization and enables faster integration of multiple battery packs into parallel operation.
Data Source
Figure 1
Figure 2a~2d
AI summary
A battery system (1) for connection to an external load (L) and a battery management method for such a system. The battery system has a plurality of battery packs (2), a plurality of unidirectional switching elements (3), a battery management controller configured to dynamically control the unidirectional switching element s(3), wherein a plurality of branches (8) are connected in parallel to each other, each branch (8) comprising a battery pack 82) connected in series with a pair of unidirectional switching elements (3) mounted in anti-parallel. The method comprises receiving an estimated impedance for each battery pack, a maximum allowable current for each battery pack, and an estimated open circuit voltage for each battery pack, calculating a maximum allowable current of the battery system based on the received information, managing the plurality of battery packs according to the calculated maximum allowable current of the battery system.